Hi everyone,
I have noticed in two sites (here and another book) that H.grandis is locally extinct in Singapore. Would someone be able to kindly reply with where is the information from? It is because a lot of other sites including IUCN states that H.grandis is considered introduced in Singapore.
Thanks so much!

Which book is that?
I don't remember where I got it from... I talked about it to Peter-Paul van Dijk: he didn't dismiss the possibility that the natural range of H.grandis once extended to Singapore.

This site says it's extinct in Singapore:

Our animal care update for this week features our Giant Asian pond turtles (Heosemys grandis). Giant Asian pond turtles are a semi-aquatic species of turtles found in South-East Asia. Unfortunately, they are considered extinct in Singapore and therefore housed at our rescue centre. Boltz, who is our biggest Giant Asian pond turtle, was found along Yishun dam where he was run over by a lorry. He endured months of pain and treatment and has since successfully recovered.
Here he is frantically trying to figure out a dietary enrichment consisting of sweet-potatoes, Banana and lychee’s. Native fruits and vegetables like Papaya and Kang-kong are favorites of these turtles. Everything from the banana leaves to the strands of dried banana leaves to tie the enrichment is kept natural to make it as safe as possible for the turtle. Providing dietary enrichments like these hope to provide the turtles with new challenges before they have access to food. This ensures that their instincts to actively seek and locate food are maintained.

Yes true, several people I spoke to were also of the opinion that it is very likely that the range extended to Singapore in the past, but no solid proof.
I got it wrong about the book reference. The book I was referring to is the ID guide to the tortoises and FW turtles by Mark Auliya, but it only states distribution within region and outside region. I mistook the reference.

Boltz stated in the story is one of our rescues, and we are trying to get release permission (for 3 of them) within Singapore, and this will also help future rescues of grandis, but need solid proof on the status

When I was working on this website I found the reference again:
J.C. Thompson collected a Heosemys grandis in Singapore in 1908. It is catalogued as CAS 16746 by the California Academy of Sciences.museums.php
The record:http://researcharchive.calacademy.org/r ... ate&Page=1
'Extinct in Singapore' was my own inference based on this single specimen. But nothing else supports it.
I modified the text on the webpage: grandis.php

Interesting to hear about Boltz. I didn't know you were working there. Please keep us updated on the status of the rescues

I've checked my available literature for the possible occurrence of Heosemys grandis in Singapore, and found no mention of the species for Singapore.

Boulenger (1912) reported it from as far south as Penang and Kedah in peninsular Malaysia; Malcolm Smith (1930) provided no additional data.

Lim & Lim (1992) did not list H. grandis in their checklist of Singaporean Reptiles and Amphibians, not as a species present in Singapore at the time of writing, and not as as a potential or unconfirmed report (in comparison, they list Batagur baska as a past occurrence).
Lim, Kelvin K. P., and Francis L. K. Lim. 1992. A Guide to the Amphibians and Reptiles of Singapore. Singapore Science Centre, Singapore. 160 pp.

The 2008 Singapore Red Data Book likewise does not refer to H. grandis at all, though they note that they only present a selection of species in their species profiles; the implication is that mainly the inconspicuous small leafliter snake species were left out.
G.W.H. Davison, RK.L. Ng and H.C. Ho (editors). 2008. The Singapore Red Data Book: Threatened Plants and Animals of Singapore. Second edition. The Nature Society (Singapore), Singapore 389466, ISBN: 978-981-08-0200-4.

Other than the CAS specimen collected by Thompson in 1908 (and in those days, 'collecting' included buying in the market), there are no records of grandis in Singapore that I am aware of. The southernmost records that I can trace are in Ipoh, with a single record (MCZ specimen) in Johor. A series of specimens in the Chicago Field Museum are from a pet shop in Perak, and the locality of the AMNH specimens, from the "vicinity of Kuala Lumpur" sound like a purchased origin as well.

So on balance, I would not think that there is a convincing case that H. grandis occurs or historically occurred in Singapore, or southern Malaysia even.